I'm just getting back into Hotokan after a break from martial in general for something like 20 years(!).
The last time I practiced Shotokan in particular is more like 30 years ago!
I've really enjoyed the return to training, but it has caused a knee injury I acquired a couple of months ago (in the gym, before I returned to the dojo) to flare up rather badly. I'm now waiting for an appointment with the physio, and in the meanwhile trying to keep myself entertained with upper body kihon and lots of reading - hence finding this site!
I had an mri on my knee a while ago as i had pains from running and karate. The surgeon said it wasn't anything obvious and he would know more when he got inside! Also said the op may not fix anything do i opted to not have it, few years on and i still get the odd pain but have given up running and really worked on technique to avoid knee twists during kicks. Good luck with it, plenty of books around while you mend.
Karate by Jesse has an article about correct knee position, correct meaning it doesn't put you in hospital. The knee moves backward and forward in one plane if you move across it isn't going to help the back foot at 45 degrees is weak and make little sense.
To treat this I use ice. Arnica and witchhazel to tackle the inflammation. Glocusomine probably spelt wrong can help the knee recover. There are various rub to reduce the swelling based ibroufin which take a couple of weeks to take effect. none of which should bother the doctor or your stomach.
Hope you get better and can enjoy your training again.
Frustrating as it may be it's probably for the best, I tried to go back to training far too soon after a knee injury many years ago and it just knocked me back even further so nothing was gained by rushing.
Bob Davis "beware of anyone who has all the answers, it's a sign you are just not asking the right questions"